Sending a message to more than 1 person?

So I love my 4s. I have had it for a week now and one thing I dont get is imessage. I sent a text to a group of people and they all got lobbed in together and started to text each other. How do you send a message to more than one person with out it doing this?

Group messaging is fun but it really drains the battery. When I first got my 4S I was apart of a group iMessage with some old Crackberry friends, but it was murdering my battery so I had to ask that they remove me.